1. Technical Field
The present invention relates generally to a chemical mechanical polishing (CMP) method and machine. More specifically, the present invention relates to a process and machine for polishing semiconductor wafers using a vertically-oriented polisher with a cleaning module for the polisher.
2. Related Art
Current CMP tool design usually includes one or more horizontally oriented polishing pads which are rotated and saturated with a slurry solution as a rotating wafer is pressed into contact with the pad. As the pad rotates, the wafer is polished. However, as the current polishing processes progress, film residuals, slurry agglomerations, pad debris and other foreign material become intermixed with the slurry and oftentimes become embedded within the pad material. As a result, the residuals, agglomerations, and debris can cause wafer scratching.
To prevent this problem, the current pad cleaning and conditioning techniques typically polish the wafers and then remove the wafer scratching particles after the wafers are removed to avoid interaction between the cleaning and polishing processes. Unfortunately, this technique slows the overall speed of the CMP process by imparting a "down time" for removal of the wafer scratching particles. As a result, the yield of polished wafers for a given polishing device is greatly reduced.